Under the Clean Water Act and Chapter 26 of the Texas Water Code, the TCEQ has the sole authority to develop and amend surface water quality standards for the state that are implemented via agency permitting programs. Under the Clean Water Act, Texas must define how water bodies will be used and must develop and enforce a comprehensive set of water quality standards. There are two components to surface water quality standards: (1) designated uses and (2) chemical, physical, and biological criteria to protect those uses.

WATERBODY USES UNDER THE TEXAS WATER QUALITY STANDARDS DESIGNATED USE PERENNIAL RIVERS AND STREAMS (MILES) LAKES AND RESERVOIRS (ACRES) BAYS (SQUARE MILES) OCEAN (SQUARE MILES) Total Unclassified* 25,955.7 1,512,773 0.0 0.0 Total Classified 14,238.3 1,552,827 2,001.6 3,879 Contact Recreation 14,151.2 1,536,415 1,996.4 3,879 Noncontact Recreation 27 524 5.2 0 Public Water Supply  8,772.7 1,517,325.0 0.0 0 Aquatic Life 14,238.3 1,552,827 2,001.6 3,879 Exceptional 624 50,270 1,304.4 3,879 High 12,867.1 1,505,033 966.5 0 Intermediate 563.1 0 0.7 0 Limited 111 524 0.0 0 Minimal** 73.1 0 0 0 Fish Consumption 14,238.3 1,552,827 1,971.8 3,879 General Use 14,238.3 1,552,827 2,001.6 3,879 Oyster Waters 0 0 1,971.8 3,879 *Presumed Use for Unclassified Waters: High Quality Aquatic Life; **Water bodies with minimal aquatic life use include three segments (1006, 1007 and 1431) which do not have a designated aquatic life use. Note: Applicants for discharge permits have the opportunity to show that the particular stream into which they want to discharge does not have existing high quality aquatic habitat. Source: Texas Surface Water Quality Standards, 2001, Appendix A.

The uses that may be established for a water body are:

• protection of aquatic life and habitat so that the water is fishable;
• use for recreation such as swimming;
• use as a drinking water supply;
• use for navigation; and
• use for industrial water supply.

A water body may be assigned more than one of these uses.

To each water body, upper and lower limits for common water quality criteria are established. Some of these criteria, or standards, are:

• dissolved oxygen,
• temperature,
• pH,
• total dissolved solids,
• fecal coliform bacteria, and
• toxic limits.

Not all waters in Texas are protected by site-specific criteria. For example, in Texas, only 14,238.3 of 40,194 perennial river miles (35 percent) and 1.55 million of 3.0 million acres of reservoirs (52 percent) have been classified for a particular use. All 2,001.6  square miles of bays and 3,879 square miles of ocean waters have been classified with site-specific criteria.^* Unclassified waters are those smaller water bodies for which site-specific study analyses have not been performed in order to set site-specific standards. Unclassified waters are protected by general aquatic life standards, which apply to all surface waters in the state.

CAUSES OF IMPAIRMENT OF SURFACE WATERS NOT MEETING DESIGNATED USES CONTAMINANT USE IMPAIRED SEGMENTS AFFECTED Fecal coliform Recreation Use 177 segments Fecal coliform and other bacteria, viruses in shellfish Oysters Water Use 14 segments Organics in fish Fish Consumption Use 19 segments Metals in fish/shellfish Fish Consumption USe/Oyster Waters Use 18 segments Depressed dissolved oxygen Aquatic Life Use 103 segments Toxicity in water Aquatic Life Use 5 segments Toxicity in sediment Aquatic Life Use 1 segment Metals in water Aquatic Life Use 7 segments Impaired fish/macrobenthos community Aquatic Life Use 7 segments Total dissolved solids General Use 12 segments Chlorides General Use 8 segments Sulfates General Use 3 segments Contaminants affecting drinking water Public Water Supply Use 2 segments pH imbalance (high or low) General Use 15 segments Totals   299 segments Note: Because segments can have multiple identified contaminants affecting multiple uses, the number of segments affected by each contaminant does not add up to the total. Source: Texas Commission on Environnmental Quality, Draft 2002 303-D List, 2002.

The EPA is required to review state water quality standards to ensure that they meet the Clean Water Act goals of "fishable and swimmable quality waters."^* States are required to evaluate and, if necessary, revise their water quality standards every three years. While most bodies of water are designated a use to meet these broad goals of swimming (contact recreation) or fishing (high or exceptional aquatic life), the Houston Ship Channel and Buffalo Bayou and Mid Pecan Bayou are so polluted that they are designated for navigation purposes only.

When the TCEQ or the EPA considers applications for wastewater discharge permits, these water quality standards are used to develop limits on the amount and type of contaminants that will be allowed in the discharge. Texas must regularly monitor the water bodies to determine whether they meet the standards, and through 1996 a water quality inventory was produced once every two years. However, in 1997 the agency divided the state into five basin planning groups. In 1998 the agency conducted a water quality assessment in two of the five basin planning groups. Beginning in 2000, the agency began conducting water quality assessments in one basin group annually, following a rotating cycle of five years.^* In 2002, the TCEQ completed a water quality inventory for the entire state.

The water quality inventory is also the basis of the Clean Water Act 303 (d) list, which identifies all "impaired" water bodies that do not meet their designated uses. Finally, the state is required to implement "watershed action plans" to restore those impaired water bodies identified in the 303 (d) list.

The basis for the watershed action plans is the development of total maximum daily loads (TMDLs) for all pollutants that prevent the attainment of water quality standards. A TMDL is an estimate, made through a detailed site-specific study process, of the maximum amount of a certain kind of pollution a body of water can receive and still meet water quality standards. A TMDL for an individual water body or stream segment may lead to stricter discharge standards or even enforcement actions against a source of pollution. The process of developing TMDLs for all impaired water bodies will take approximately a decade.^*

Antidegradation Policy

Under the Clean Water Act, each state must develop a statewide antidegradation policy for protecting water quality while allowing the discharge of wastewater into water bodies.^* In Texas, this antidegradation policy is developed as part of the state's surface water quality standards.

The antidegradation policy consists of three parts (or tiers). The first tier provides a minimum level of protection to all waters by prohibiting any activity that could affect the existing use (for example, swimming, fishing) of the water, although its overall quality may be affected. A second tier is applied to those water bodies which have a "high" quality of water and prohibits any degradation of these waters, even if they can still meet their designated use. Thus, the TNRCC could deny a wastewater discharge permit on the grounds that it would degrade a high-quality water. However, if such an activity—and the resulting degradation—is demonstrated to be economically and socially justified, the permit can be granted.

The third and most restrictive tier of the antidegradation policy allows states to designate Outstanding National Resource Waters, or ONRWs. These water bodies receive the highest level of protection under state water quality standards. Unlike the provisions for high-quality waters, no activity that would degrade such waters would be allowed, even if they were economically or socially needed by the region. Thus, additional wastewater discharge permits or construction requiring storm-water permits would probably not be allowed in an ONRW watershed.

In 1994 the then-TNRCC proposed designating Christmas Bay, South Bay near Port Isabel, Caddo Lake, stream segments in Guadalupe Mountains National Park, and Barton Creek and Barton Springs in Austin as the state's first ONRWs. However, the TNRCC, after receiving opposition from many regulated sources of pollution and from political representatives, later chose not to request ONRW designation for these five water bodies. In contrast, there are approximately 70 ONRWs designated in Arkansas, 40 in Louisiana, and 120 in Oklahoma.^* In the current version of the Texas Surface Water Quality Standards, no waterbodies have been designated to receive this special protection.

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